Turbine cooling



United States Patent 3 O 3,370,830 TURBINE COOLING Lawrence H. Nickles,Allestree, Derby, England, and John E. Harper, Greenwood, Ind.,assiguors to General Motors Corporation, Detroit, Mich., a corporationof Delaware Filed Dec. 12, 1966, Ser. No. 601,067 7 Claims. (Cl.253-3915) ABSTRACT OF THE DISCLOSURE Air-cooled turbine blades aremounted on a turbine rotor, the rotor rim and blade roots definingcommunicating passages for cooling air. A tube mounted within thepassages and extending into both the rotor and the blade root minimizesleakage through the gap between the rim and root. The tube is retainedby being lodged against shoulders at the bottoms of counterboresin-these two structures, one end of the tube being flared or expanded sothat it cannot fall out of the hole through which it is originally movedinto place.

Our invention in one aspect relates to turbines and particularly tostructure for feeding cooling air or other cooling agents to turbineblades. In another aspect, the invention relates to an improvedconnection between two bodies such, for example, as a turbine rotor anda rotor blade to conduct a fluid and to reduce or minimize leakage. Instill another aspect, our invention may be regarded as an improvement inthe retention of tubes interconnecting two structures.

In the preferred embodiment of the invention air-cooled turbine bladesare mounted on a turbine rotor, the rotor rim and blade roots definingcommunicating passages for cooling air. A tube mounted within thepassages and extending into both the rotor and the blade root minimizesleakage through the gap between the rim and root. The tube is retainedby being lodged against shoulders at the bottoms of counterbores inthese two structures, one end of the tube being flared or expanded sothat it cannot fall out of the hole through which it is originally movedinto place.

The principal objects of the invention are to improve the efficiency ofturbine rot-or cooling, to provide a connection minimizing leakage inthe transfer of fluid from a rotor or structure to a blade more or lessloosely mounted on the rotor, and to provide a fluid conductingstructure which is simple and easily installed and which is safe againstdislodging. A further object is to provide an improved method ofcompleting an installation of the character referred to. The nature ofour invention and its advantages will be apparent to those skilled inthe art from the succeeding detailed description and accompanyingdrawings of preferred embodiments of the invention.

FIGURE 1 is a partial sectional view of a turbine rotor wheel and ablade mounted thereon, the section being taken on a plane containing theaxis of the wheel.

FIGURE 2 is an enlarged fragmentary view illustrating a first step inthe fitting of the interconnecting tube.

FIGURE 3 is a similar view illustrating a further step.

FIGURE 4 is a similar view illustrating the final or swaging step in theassembly.

FIGURE 5 is a view similar to FIGURE 4 illustrating modifications ofstructure.

Referring first to FIGURE 1, a turbine wheel 9 having a rim 10 mounts aring of blades 11. Each blade includes a platform 13, a stalk 14, and aroot 15. The blade root is mounted in an appropriate slot 17 in the rim;as illustrated, the root and slot are of the well-known multiple ICCdovetail type. Sealing plates or rings 18 and 19 extending around therotor between the rim and the blade platforms serve to enclose the spacebetween the ring of blade platforms and the rim. Each blade includes anentry passage 21 for cooling air extending from the base of the rootinto a chamber 22 within the blade from which it is discharged throughany sort of openings in the blade or in the outer shroud 23 of theblade. The structure of the blade is immaterial to our invention. Thecooling air reaches the passage 21 through a passage 25 in the rimaligned with passage 21, to which it is supplied by any suitable means(not illustrated).

Referring now to FIGURE 2 which shows the structure to larger scale, thepassage 25 is defined by a bore 26 and a counterbore 27 of slightlylarger diameter than bore 26. The passage 21 is defined by a counterbore29, preferably approximately the same diameter as counterbore 27, and bya bore 30 of smaller diameter than bore 26. While there may be somedeparture from a coaxial relation between the several bores andcounterbores, preferably they are all coaxial. This structure provides ashoulder 31 within the rim and a shoulder 33 within the blade root.Since the blades normally are mounted somewhat freely in the slot, thereis typically a clearance at 34 between the base of the blade root andthe bottom of the slot in the rotor.

According to our invention, this gap is bridged, by a short tube 37which, as indicated in FIGURES 2, 3, and 4, is introduced through thebore 26 which is large enough to allow the tube to enter freely. Tube 37preferably is just long enough to reach from shoulder 31 to shoulder 33when it has been pushed into place. As illustrated in FIGURE 3, thediameter of bore 30 is preferably approximately the same as the interiordiameter of the tube so that the upper end of the tube lodges againstthe shoulder 33. The tube is retained, and a sealing relation to therotor is preferably created, by swaging or expanding the tube, as shownin FIGURE 4. A punch 38 having a conical point 39 and of such diameteras to slide freely within the bore 25 is introduced against the rim endof tube 37 and is driven slightly into the tube with a hammer or otherinstrument so that the rim end of the tube is swaged outwardly, asindicated at 41 in FIGURE 4. This swaging enlarges the tube so that itcannot drop out of the passage 25 and also preferably seats the outerwall of the tube firmly against the circumferential wall of thecounterbore 27.

Note that the swaged portion does not extend into the blade root, andthe major part of the tube has some clearance from the blade root andrim. Thus, the tube does not interfere with some shifting of the bladein response to forces acting upon it. In other words, the tube 37 is nota blade locking pin. The blade root may be retained by any suitableknown structure as, for example, by the sealing rings 18 and 19.

The angle of the point 39 of the punch is not critical, but an angle ofabout 60 is preferred. The material of the tube 37 may vary dependingupon the temperature level which it must withstand in operation of theturbine. Since the tube 37 closely abuts the shoulder 33 and theshoulder 31 and also preferably is in a rather tight fit within thecounterbore 27, leakage through gap 34 is minimized. It will be seenthat it is contemplated that the difference in radius between the bores25 and 27 is approximately the thickness of the tube 37. The end 39 ofpunch 38 may be used to insert the tube as well as to expand it.

FIGURE 5 illustrates two modifications. In this case, the structure ofthe rim 10 is the same as that previously described and the blade root15' may differ only in that the shoulder 33 is conical.

FIGURE 5 also illustrates a punch 38 which adds a feature to the punchpreviously described in that the body .of the punch-is steppediqapiovide a shoulder 43 which engag -sti e m .101 cont ol the, depth o nsrt n o the tool.

The foregoing descriptionof preferred embodiments of The ease ofinstallation of the tubes 37 ,isobvious. The blade maybe removed upondisassembly of the rotor by shearing the tube 37 by movement of theblade root in its slot.

The detailed description of the preferred embodiment of the inventionfor the purpose of explaining the principles thereof is ,notto beconsidered as limiting or restrict ing the invention, as manymodifications may be made by the exercise of skill in the art.

We claim:

1. A structure for directing 'a fluid from a first body in o et ond ycompri ing, .inecombination:

a first body, V

a second body juxtaposed to the first body, and

.a tubeextending into both bodies;

the first body having a bore of larger diameter than the 'norrnaloutside diameter of the tube and having a counterbore, substantiallycoaxial with and ,ofgreater diameter than the bore, extending to thesurface of the body adjacentto thesecond body,

the second body having a bore of smaller diameter than the normaloutside diameter of the tube and having a counterbore larger than thenormal outside diameter of the tube aligned with the .counterbore in thefirst bo y, V

4 t the tube being seated aaginst the bottom of the counterbore inthesecond body and having a radially expanded end retained in thecounterbore in the first body. 7 V

2. A structure as recitedin claim 1 in which the radially expanded endis seated againstthe bottom of the counterbore in the first body. Y V

3. A structure as recited in claim 1 in which the radially expanded endis expanded into a close fit with the circumferential wall of thecounterbore.

4. A structure as recited in claim 3 in which the radially expandedendis seated against the bottom ofthe counterbore in the first body.

5. A structure as recited in claim 1 in which one of the bodies is ablade-mounting part of a turbine and the other is a turbine blade.

6. A structure as recited in claim 1 in which one of the bodies is aturbine rotor and the other is a turbine blade.

7. A structure as recited in claim 1 in which the first body is aturbine rotor and the second body is a turbine blade root.

References Cited UNITED STATES PATENTS 2,930,580 3/1960 Hayes 25339.152,931,623 4/1960 Hyde 25339.15 3,219,314 11/1965 Petrie 253--39.153,295,826 1/ 1967 Nickles 253'--77 EVERETT A. POWELL, JR., PrimaryExaminer.

